Why did Hashem not ask the snake why he sinned (like He asked Adam and Chavah)?

1.

Rashi: Because it was a Mesis
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(an inciter to sin) and one does not give a Mesis an opportunity to defend himself. Had He asked it that question, it would have answered 'If the Rav (in this case, Hashem) issues a command, and the Talmid revokes it, whom does one follow?'

Riva, Moshav Zekenim (verse 4):
A Mesis is only for idolatry! Also this was like idolatry, for it said "you will be like Elokim."

2)

What did Hashem mean when He told the snake that it was more cursed than all the animals and the wild beasts of the field?

1.

Seforno: He meant that it would from now on attain its desires and its needs with difficulty and in a less pleasurable way than all other creatures,
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as it goes on to explain "You will crawl on your belly".
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2.

Rashi (citing the Gemara in Bechoros): Commenting on the need to add "the wild beasts ... ", Chazal explain that, just as the pregnancy of the latter lasts seven times as long as that of the former, so too, does the pregnancy of a snake last seven times as long as other wild beasts
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- i.e. seven years, as opposed to one.

Commenting on the words "And you will eat earth ... ", the Seforno adds - 'You will not attain the pleasures that you would have enjoyed before you sinned - eating and drinking and being intimate, as happened to a certain extent, to Yisrael, as the Gemara records in Sotah (49a).

This is a punishment only for females! Therefore, He added "you will crawl on your belly and eat earth", which apply also to males. These were Midah k'Neged Midah, for it caused Adam's height to be lowered, and that he would return to earth (Moshav Zekenim).

3)

Eating earth is a benefit - its food is always available!

1.

Moshav Zekenim #1: Even if it eats the tastiest food, it tastes earth. Also, it will need to toil as much as other animals.

2.

Moshav Zekenim #2, from Midrash Agadah: It does not feel satisfied until it eats earth.

Perhaps this is like the difference between Eretz Mitzrayim and Eretz Yisrael (Devarim 11:10-11). Eretz Yisrael depends on rain, which forces us to turn to Hashem (just like in the Midbar, people did not have food for tomorrow, so they turned their hearts to Hashem - Yoma 76a). Mitzrayim relies on the Nlie (and does not turn to Hashem). Similarly the snake does not turn to Hashem, unlike other animals - "Einei Chol Elecha Yesaberu..."! (PF)

4)

What does "Kol Yemei Chayecha" include?

1.

R. Bechayei: It will eat dirt even in the days of Mashi'ach. We learn from remembering Yetzi'as Mitzrayim "Kol Yemei Chayecha".

2.

Peninim mi'Shulchan ha'Gra: It will not be cured (able to walk again) even when others are cured in the days of Mashi'ach. We learn from remembering Yetzi'as Mitzrayim "Kol Yemei Chayecha."